A dockable computer system includes a portable computer, usually a notebook or laptop, and a stationary or base computer unit having a docking station for receiving the portable unit. Dockable computer systems may be operated in a docked state in which both computer units are physically associated as a generally unified system or the remote unit may be separated from its host for independent operation in the undocked state.
Rudimentary docking systems of the foregoing variety have been designed in an effort to meet the needs of today's mobile computer users for "ubiquitous" computing system capabilities, to fulfill their computing needs in diverse aspects of their professional and personal lives and in sundry locations. Contemporary dockable computer systems approach this problem through a single system capable of operating as an expandable desktop computer having a detachable mobile computing unit.
The expandable desktop computer provides greater storage resources, network connectivity, larger displays, and other superior facilities which are necessary for the typical range of generally demanding home and office computing. The portable computer (mobile computer unit) allows the user to have computing capabilities while outside the home or office by detaching that component with its indigenous hardware and resident software. The computing capabilities of the portable computer are somewhat limited due to size, weight and power constraints but represent the best available approach in these embryonic attempts to balance portable mobility needs.
When the user leaves the host environment of home or office, the portable computer is undocked (that is, physically detached) from the docking station of the stationary computer unit. Applications, files, and other data needed for the mobile computing task must have previously been stored in the portable computer. When the user returns to the host environment, the portable computer is reunited with the docking station so that the applications, the files, and other data are stored and maintained in a single location. Thus, the use of a dockable computer system allows the user to have access to any needed applications, files, and other data just before embarking on the mobile computing task.
When the dockable computer system changes states from the undocked state to the docked state (a docking event), protective measures are required to prevent signaling failures, bus crashes, and component damage caused by physically connecting the active buses of the portable computer and the docking station. Contemporary dockable computer systems are "cold docking" systems which protect the buses by powering off the portable computer and docking station. Powering off the portable computer and docking station renders the buses inactive so that the protective measures are not required. These "cold docking" systems are disadvantageous because the user must wait for the dockable computer system to be turned on, rebooted, and reconfigured before the dockable computer system is operational in the docked state.
Further, these contemporary dockable computer systems generally utilize mechanical switches to sense a docking event. Mechanical switches are disadvantageous because they are impractical for transferring information necessary for conveniently docking the portable computer with the docking station. Also, mechanical switches require accurate alignment and are prone to wear. Thus, contemporary docking systems meet only the physical needs of a "ubiquitous" computing system but do not address the convenience and communication needs of the users of such a system.
There is a need for a dockable computer system which includes a communication system for generating an advanced notice signal which warns of a docking event so that the protective measures may be employed. Further, the advance warning signal enables the portable and host computer units to otherwise provide for the docking event by preparing certain applications, files, or other data for immediate access. Also, there is a need for a communication system for transferring parameters necessary for the employment of sophisticated protective measures which allow active buses to be connected. Such a communication system enables a dockable computer system to be conveniently docked and operational in a minimal amount of time. Thus, there is a need for a dockable computer system having a communication link providing advanced warning of an impending docking event.